Fluorine-Doped Cesium Tungsten Bronze-Integrated Thermally Responsive Poly( N -isopropylacrylamide- co -acrylamide)-Based Copolymeric Smart Hydrogel Films for NIR Shielding

Abstract Developing advanced materials and composites to counter the global energy crisis arising from climate change is one of the crucial research areas nowadays. In this context, the present research reports the successful fabrication of a high-performance thermoresponsive hydrogel film for thermochromic light regulation and solar NIR shielding applications. Poly(N-isopropylacrylamide-co-acrylamide) (PNAM) copolymeric hydrogels integrated with a biobased acrylated epoxide methyl ricinoleate (AEMR) monomer are prepared through free radical polymerization with a tunable lower critical solution temperature (LCST) in the range of 35−40 °C. The dark blue-colored fluorine (F−)-doped cesium tungsten bronze Cs0.33WO3−xFx (FCWO) nanoparticles are synthesized via a facile hydrothermal route to enhance the near-IR (NIR) blocking capacity of the films. The optimized composite hydrogel film (PNAM-FCWO-0.3 film with 0.37 mm thickness) displayed a visible light transmittance (Tlum) of ∼70.03%, a remarkable solar modulation (ΔTsol) of ∼67.99%, and high NIR shielding of ∼89%. Moreover, the optimized composite hydrogel film (PNAM-FCWO-0.3) decreased the internal temperature of the model house by ∼10.8 °C compared to the standard glass window-based identical model house. With its excellent flexibility, water stability, and heat absorption capacity, the PNAM-FCWO composite films show significant potential for fabricating smart hydrogel films for NIR shielding and energy saving applications.